(Ephesians 4:4-6) There is one body, and one Spirit, even as ye are called in one hope of your calling; One Lord, one faith, one baptism, One God and Father of all, who is above all, and through all, and in you all. There's no doubt that the baptism of the Holy Spirit is important. There is also no doubt that baptism in water is commanded. So which one is Paul talking about in Ephesians 4:5. I believe he is talking about both of them as two aspects of a single event. Acts 2:38 promises that when we are baptized we will receive the gift of the Holy Spirit. Therefore there is a physical aspect of baptism (water) and a spiritual aspect of baptism (the Holy Spirit), but there is only one baptism.
There is only "one baptism" worthy of important mention:
(Mark 1:8) I baptize you with water, but he will baptize you with the Holy Spirit.
The baptism of the Holy Spirit.
The "One baptsim" in Eph 4: 5. Is the Spiritual baptism into the body of Christ,
1 Cor 12: 13. The rebirth. Jn 3: 3--8.
Some of the disciples were born again in Jn 20:22.. Peter was, Becaue one of the Greek wprds for, "Love" in Jn 21: 15--17, Is, "Agape", The love of God, You can only have this if you are born again. Rom 5: 5.
The disciples were born again in Acts 8: 14--16, But weren't baptised in the Holy Ghost intil v17.
Paul was born again in Acts 9: 6, But wasn't baptised in the Holy Ghost intill at least 3 days later, V 9. & v17.
This was before he was baptised in water.
The Gentiles in Acts 10: 44--46 were saved,[Born again] Baptised in the Holy Ghost and spoke in tongues....But they weren't baptised in water.
The disciples were baptised in water but they weren't saved until some of them was in Jn 20: 22., The rest on the day of pentecost.
As for Acts 2: 38. The Bible translaters have mislead us into believing water baptism saved,..But this is the way the original Greek scripture puts it, And this is the way the people would have heard and understood it,
"Repent for the remission of sins, And you shall receive the gift of the Holy Ghost".
Then you can be baptised in water.
The Greek emohesis for, "Remission" is on , "Repent", Not baptim.
The Greek emphesis for, "Saved" in Mk 16: 16, Is on, "Beleveth" Not baptism.
Acording to the original Greek, Water baptism is,
"The expression, Not the medium, The symbol, Not the cause".
So the Greek and the Bible [If you know it] proves water baptism doens't save, And the "ONE" baptism is the rebirth.